why did my resin cure so oily?

Hi all,

Hope someone can help me solve my mystery. I am repairing a very large delam but have had to use some resourcefullness because I can’t seem to purchase much surf specific material where I am living. I tried to buy resin and cloth at the local surf shop but they wouldn’t sell it but instead guided me to a nearby marine store where they indeed had fiberglass cloth (no idea whether it’s 4 or 6 oz.) and resin. Seems they buy the resin and catalyst in large quantities and then dispense it into smaller containers to sell to the public. My resin can has “NESTLE” stamped into the lid and no instructions or even a label on the sides. The can must have been intended for hot cocoa mix unless the company is venturing into new markets. Anyway, the guys there couldn’t tell me whether the stuff was laminating or hot coat but I asked if it could be sanded after curing and they said OK. As they didn’t sell Qcell or any filler, I scoured Swaylocks and read that flour, talcum or even sugar can be substitutes. Since I am in Brazil, the world’s principal grower of sugar cane, I decided to go with the flow! I think I should have used confeccioner’s though because table sugar is a bit grainy. Anyway, the potion cured super hard and I am having a helluva time sanding it so thought about just laying over a thin coat of plaster wall paste (another Swaylock suggestion!) which I know would be easier to shape but the cured resin is very oily. I sanded one small part for some time and it seemed be dry afterwards but a few hours later, it was oily again, though a bit less than before. My question is, could this be the surfacing agent seeping out? and if so, how long should I wait until it’s done? Also, can I use some acetone or thinner to wipe it off or must it be sanded off?

Anyway, since I have the wall paste, I am going to try filling some pressure dings for cosmetic reasons only (no water issues). If the plaster stuff holds then I might give the whole board a once over with it, cover the patches with swatches of fiberglass cloth and then paint the whole board. If the paster falls out of the ding, I might try again but with a few tiny plastic screws partially driven into the board so the plaster has something to cling to. I’ve read that some Swaylockers have had success with Bondo so that might be stage 3 if it goes that far. I don’t have a job at the moment so what the hell.

Thanks to everyone for making this site such a great resource!!

sounds like too much catalyst,epoxy correct?

get a pot scrubber(green scrunge pad) and soap/running water.

or my fav..........de-natured alcohol.

not personnal,but like in northshore,"scrub it kook !"



Thanks for the suggestions Herb! Nevertheless, after waiting a couple of days, which can be attributed to a combination of patience and laziness, it seems the oil has dissipated on its own but I think you were right, probably too much catalyst, or maybe too much SA. Or maybe it was the super high humidity here that was coaxing spmething out of the resin. Anyway, now I have sanded it down as much as possible and applied the plaster to smooth out the oatmeal lumpiness. The wall paste shapes very nicely but don’t know how it will stand up after laying the cloth on top. In theory, it only has to withstand compression forces and as long as no water gets in, should be OK. I would think though that bondo is a better option though. Tomorrow I laminate!

First you didn't say epoxy or polyester resin. If it was epoxy and you got it from a marine shop you probably have amine blush and because it was hummid it would blush more. Do as Herb says and just wash it off with water and a green pad. Standard ops for boat builders.If you wash the blush off so your sand paper wont clog.It takes about 2 days for the resin to be hard enough to sand. I would not use sugar or flour as a filler. Talcum is ok but dries hard. sanding dust from a belt sander works good except its gonna be a dark color.

Hey Wood Ogre, thanks for the response. The fact is that I have no idea whether the resin is poly or epoxy because the store owner poured it from a larger container (I supposed) into an unmarked can and sold is as “resin for fibergalss mat”. From what I have seen and what you wrote, I think you are spot on though and it must be that marine stuff because after about 2 days, it finally did get hard and I was able to sand the top layer off. It cured like cement though and I had to muscle it but it’s ready now for laminating. You’re right about the sugar too, not the best choice for its graininess. I’ll be back in the US for a visit in September so will make sure to buy some Qcell and bring it back with me for the next inevitable dings and delams I’ll have to address.

I’m actually very glad to have bought this repair material because I picked up a second surfboard to use while I am repairing my first and I’ve promplty installed two open dings in it - one while surfing and one while moving it around at home. Wish these boards weren’t so fragile. Anyway, part of the game I guess, I’ll patch them up when I laminate.


     Howzit sweeed, Did you use catalyst to kick it off or did it come as a 2 to 1, Since you bought it at a marine shop I would think it would be marine poly ,but these ays they are making boats with epoxy also. One thing about boat poly is you can sand it after lamination with out a sanding coat. I would go back to the shop and ask some questions about the resin/epoxy and find out which one it is. Aloha,Kokua

OK, so the mystery begins to unfurl. I laminated yesterday, 2 layers on the rear third of the deck right down to the bottom of the rails. This was a large delam. The resin is the old 2 part type and I mixed 50:1 and was spreading it out when it started to kick prematurely. I’d say after only about 10 -12 minutes. The resin in my mixing can heated and hardened pretty fast but the resin I had spread on the board took a good long while longer to cure. Good thing though because I couldn’t get the fiberglass to wrap under the rails and stick to the bottom. Part of the reason was that I had run out of wet resin and couldn’t saturate the cloth with more so I began cutting up strips of packing tape and applied about 20 or so pieces all around to hold the glass in place underneath. After a few hours, I removed the tape without issues but will surely have to lay a strip of glass on the edge of the rail to make sure it’s water tight. I also have some air bubbles that I’ll have to fill in or maybe cut out and glass over. Good thing is it’s rock solid and sandable so I imagine it was standard marine glass resin. It’s looking pretty hodgepodge what with old sun tanned foam, my filller concoction of resin and sugar and then wall repair paste all visible beneath so I’ll paint over it to keep it a secret.

So now the strange part about the resin is that this time it cured without any oily film! I am guessing now that the slime had something to do with my mixing the resin with sugar to make a filler. Don’t know if anyone else has encountered this but it seems to be a good argument against using sugar as a Q cell substitute. Time now to sand it all down by hand. Don’t have access to any machines but that’s OK, this way I get a work out that will make me a stronger paddler, and god knows I need help in that department.